The present invention relates to an improved stud driver or coupling member for inserting or driving threaded studs into structures containing threaded holes. This most usually is required for holding members together such as holding various covers on an automobile crankcase, holding flanged couplings together or otherwise in general industrial maintenance work or any other assembly operation that would require the use of threaded headless studs. It is well-known that when such headless studs are installed, it is necessary that the installation occur with a considerable amount of torque so that the studs will be tightly secured in place. Therefore, in order to apply the torque essential to drive each stud, it is necessary that the stud be firmly gripped and preferably in a manner that does not damage the stud threads especially at the end of the stud which is to be exposed from the structure since to destroy such threads could render the stud useless. On the other hand, it is essential that the tool used to drive the stud into the threaded hole must be not so firmly engaged with the stud that it is impossible to remove the tool without back rotating the driven member and thus effecting the degree to which the stud has been secured in the threaded hole.
The present invention provides an extremely inexpensive simple and efficient tool which effectively eliminates the back rotating problem associated with known prior art devices and reduces frictional forces during the period when the tool is being removed from the stud.
Examples of known prior art stud wrenches are shown in the following U.S. Pat. Nos.: Bayes, 2,336,157, Goldberg 2,521,910, Tann et al. 2,933,960, Williams 2,199,721.
The device disclosed in Goldberg makes use of an internally threaded tool which has a removable transversely extending hardened solid pin. The hardened pin serves as a removable abutment for the end of a stud when the device is used to drive the stud into a threaded hole. To remove the device from the stud it is presumed that the hardened pin is removed so that the grip on the stud is thereby released. The stud driver disclosed in Bayes employs a horizontally sliding tapered pin or a wedge member which is provided with an inclined surface and a locking plug which is vertically movable. The bottom end of the locking plug directly engages the end stud to be driven while the upper end of the plug engages the inclined surface of the wedge member when the wedge member is moved sideways in a first direction. The locking plug is released when the wedge member is moved in the opposite direction to the first and also thereby releases the driving force exerted on the gripped end of the stud. Williams discloses the use of a driving tool which is provided with a threaded bore for receiving the stud to be driven and a hardened ball bearing at the end of that bore which acts as an abutment against which the exposed end of the stud will strike.
Tann et al. discloses the use of a longitudinally movable anvil which serves to lock together the stud to be driven and the drive member which is threadily engaged with the stud member being driven. The anvil is provided with a circular head which in locking the drive member and the stud together abuts the interior of the tool along a relatively large flat surface relative to the size of the end of the stud. In theory, after the stud has been driven into place the driven member is more easily rotatable within the tool than is the stud within the threaded socket in which it has been driven so that backward rotation of the drive member within the tool releases the engagement between the head of the anvil and the interior of the tool so that the locking relationship between the drive member and the stud is also released.
Problems exist with each of these prior art devices however, primarily in overcoming the effects of deforming the abutment devices and the frictional contact between the drive member and the stud being driven so as to allow easy removal of the tool from the stud without back rotating or removing the stud from its driven position within the threaded bore into which it has been driven. Likewise, additional problems exist in producing tools which can be used for powered rotation either with drills or with impact wrenches. In addition, none of the prior art devices employ a stop member within the driving tool which is in any way resilient in order to minimize the effects of the stop member on the end of the stud being driven.
Therefore, the primary object of the present invention is to provide a stud driving tool which provides sufficient frictional engagement to effectively transfer torque from the tool to the stud being driven so that the stud can be tightly secured in a threaded hole. In addition, it is an object of the present invention to make use of a resilient stop member located within the threaded bore of the tool that will by its springy nature allow for an easy release of the stud and effectively eliminate any back rotation of the stud upon removal of the tool therefrom. In addition, it is an object of the present invention to provide a stud driving tool which has no members protruding therefrom or beyond the exterior surfaces of the tool so that it can be safely used with power equipment.
A still further object of the present invention is to make use of a resilient stop member which can bend in response to the driving torque applied to the stud and to also assist in releasing the end of the stud and thereby effectively eliminating any back rotation. Further, it is an object of the present invention to employ stop member which has a very small amount of surface contact with the end of the threaded stud being driven so that driving torque can be effectively transmitted to the threaded stud but because there is a small amount of resistance at the point of contact and due to the resiliency of the rolled pin, release of the stud is easily effected.